This invention is directed to subcutaneous cavity marking devices and methods. More particularly, a cavity marking device and method is disclosed that enable one to determine the location, orientation, and periphery of the cavity by radiographic, mammographic, echographic, or other non-invasive techniques. The invention typically is made up of one or more resilient bodies and a radiopaque or echogenic marker.
Over 1.1 million breast biopsies are performed each year in the United States alone. Of these, about 80% of the lesions excised during biopsy are found to be benign while about 20% of these lesions are malignant.
In the field of breast cancer, stereotactically guided and percutaneous biopsy procedures have increased in frequency as well as in accuracy as modern imaging techniques allow the physician to locate lesions with ever-increasing precision. However, for any given biopsy procedure, a subsequent examination of the biopsy site is very often desirable. There is an important need to determine the location, most notably the center, as well as the orientation and periphery (margins) of the subcutaneous cavity from which the lesion is removed.
In those cases where the lesion is found to be benign, for example, a follow-up examination of the biopsy site is often performed to ensure the absence of any suspect tissue and the proper healing of the cavity from which the tissue was removed. This is also the case where the lesion is found to be malignant and the physician is confident that all suspect tissue was removed and the tissue in the region of the perimeter or margins of the cavity is xe2x80x9ccleanxe2x80x9d.
In some cases, however, the physician may be concerned that the initial biopsy failed to remove a sufficient amount of the lesion. Such a lesion is colloquially referred to as a xe2x80x9cdirty lesionxe2x80x9d or xe2x80x9cdirty marginxe2x80x9d and requires follow-up observation of any suspect tissue growth in the surrounding marginal area of the initial biopsy site. Thus, a re-excision of the original biopsy site must often be performed. In such a case, the perimeter of the cavity must be identified since the cavity may contain cancerous cells. Identification of the cavity perimeter necessary to avoid the risk of opening the cavity, which could release and spread cancerous cells. Moreover, the site of the re-excised procedure itself requires follow-up examination, providing further impetus for accurate identification of the location of the re-excised site. Therefore, a new marker will be placed after re-excision.
Prior methods of marking biopsy cavities utilize one or more tissue marking clips as the biopsy site marking device. Most commonly, these marker clips have a xe2x80x9chorseshoexe2x80x9d configuration. The marker clips attach to the walls of the cavity when the free ends or limbs of the xe2x80x9chorseshoexe2x80x9d are pinched together, trapping the tissue. This device has significant drawbacks.
For instance, prior to placing the marker clip at the cavity site, the site must be thoroughly cleaned, typically by vacuum, to remove any residual tissue debris. This minimizes the possibility that the marker clip attaches to any loose tissue as opposed to the cavity wall. Once the cavity is prepared, the clip must be examined to ensure that the limbs of the clip are substantially straight. If the limbs have been prematurely bent together, the clip will be discarded since it will most likely not attach properly to the cavity wall. Actual placement of the clip often requires additional vacuum of the cavity wall to draw the wall into the aperture between the limbs of the marking clip so that a better grip is obtained between the limbs of the clip. Additionally, there is always the possibility that the clip may detach from the cavity wall during or after withdrawal of the tools used to place the clip into the cavity.
Aside from the problems inherent in the placement of the marking clip, there are also limitations associated with how well the marking clip can identify a biopsy cavity. As the marking clip must trap tissue for proper attachment, in cases of endoscopic placement, the clip can only be placed on a wall of the cavity substantially opposite to the opening of the cavity.
Moreover, patient concern limits the number of clips that may be placed in a cavity. As a result, the medical practitioner is forced to identify the outline of a three dimensional cavity by a single point as defined by the marking clip. Obviously, determination of the periphery of a biopsy cavity from one point of the periphery is not possible.
These limitations are compounded as the biopsy cavity fills within a few hours with bodily fluids, which eventually renders the cavity invisible to non-invasive techniques. Another difficulty in viewing the clip stems from the fact that the clip is attached to the side, not the center, of the cavity. This makes determining the spatial orientation and position of the cavity difficult if not impossible during follow-up examination. Additionally, during a stereotactic breast biopsy procedure, the breast is under compression when the marking clip is placed. Upon release of the compressive force, determining the location of the clip can be unpredictable, and the orientation as well as the location of the periphery of the cavity are lost.
The marker clip does not aid in the healing process of the biopsy wound. Complications may arise if the marker strays from its original placement site. As described above, if a re-excision of the site is required, the marker clip may also interfere when excision of a target lesion is sought.
Other devices pertaining to biopsy aids are directed to assisting in the healing and closure of the biopsy wound; thus they do not aid the clinical need or desirability of accurately preserving the location and orientation of the biopsy cavity. See, e.g., U.S. Pat. Nos. 4,347,234, 5,388,588, 5,326,350, 5,394,886, 5,467,780, 5,571,181, and 5,676,146.
This invention relates to devices and procedures for percutaneously marking a biopsy cavity. In particular, the inventive device is a biopsy cavity-marking body made of a resilient, preferably bioabsorbable material having at least one preferably radiopaque or echogenic marker. The device may take on a variety of shapes and sizes tailored for the specific biopsy cavity to be filled. For example, the device in its simplest form is a spherical or cylindrical collagen sponge having a single radiopaque or echogenic marker located in its geometric center. Alternatively, the body may have multiple components linked together with multiple radiopaque or echogenic markers.
A further aspect of the invention allows the marker or the body, singly or in combination, to be constructed to have a varying rate of degradation or bioabsorption. For instance, the body may be constructed to have a layer of bioabsorbable material as an outer xe2x80x9cshell.xe2x80x9d Accordingly, prior to degradation of the shell, the body is palpable. Upon degradation of the shell, the remainder of the body would degrade at an accelerated rate in comparison to the outer shell.
The device may additionally contain a variety of drugs, such as hemostatic agents, pain-killing substances, or even healing or therapeutic agents that may be delivered directly to the biopsy cavity. Importantly, the device is capable of accurately marking a specific location, such as the center, of the biopsy cavity, and providing other information about the patient or the particular biopsy or device deployed.
The device is preferably, although not necessarily, delivered immediately after removal of the tissue specimen using the same device used to remove the tissue specimen itself Such devices are described in pending U.S. patent application Ser. No. 09/145,487 (Attorney Docket No. 41269-20002.00), filed Sep. 1, 1998 and entitled xe2x80x9cPERCUTANEOUS TISSUE REMOVAL DEVICExe2x80x9d, and pending U.S. patent application Ser. No. 09/184,766 (Attorney Docket No. 41269-20001.20), filed Nov. 2, 1998 and entitled xe2x80x9cEXPANDABLE RING PERCUTANEOUS TISSUE REMOVAL DEVICExe2x80x9d the entirety of each are which hereby incorporated by reference. The device is compressed and loaded into the access device and percutaneously advanced to the biopsy site where, upon exiting from the access device, it expands to substantially fill the cavity of the biopsy. Follow-up noninvasive detection techniques, such as x-ray mammography or ultrasound may then be used by the physician to identify, locate, and monitor the biopsy cavity site over a preferred period of time.
The device is usually inserted into the body either surgically via an opening in the body cavity, or through a minimally invasive procedure using such devices as a catheter, introducer or similar type device. When inserted via the minimally invasive procedure, the resiliency of the body allows the device to be compressed upon placement in a delivery device. Upon insertion of the cavity marking device into the cavity, the resiliency of the body causes the cavity marking device to self-expand, substantially filling the cavity. The resiliency of the body can be further pre-determined so that the body is palpable, thus allowing tactile location by a surgeon in subsequent follow-up examinations. Typically, the filler body is required to be palpable for approximately 3 months. However, this period may be increased or decreased as needed.
The expansion of the resilient body can be aided by the addition of a bio-compatible fluid which is absorbed into the body. For instance, the fluid can be a saline solution, a painkilling substance, a healing agent, a therapeutic fluid, or any combination of such fluids. The fluid or combination of fluids may be added to and absorbed by the body of the device before or after deployment of the device into a cavity. For example, the body of the device may be pre-soaked with the fluid and then delivered into the cavity. In this instance, the fluid aids the expansion of the body of the device upon deployment. Another example is provided as the device is delivered into the cavity without being pre-soaked. In such a case, fluid is delivered into the cavity after the body of the device is deployed into the cavity. Upon delivery of the fluid, the body of the device soaks the fluid, thereby aiding the expansion of the cavity marking device as it expands to fit the cavity. The fluid may be, but is not limited to being, delivered by the access device.
By xe2x80x9cbio-compatible fluidxe2x80x9d what is meant is a liquid, solution, or suspension that may contain inorganic or organic material. For instance, the bio-compatible fluid is preferably saline solution, but may be water or contain adjuvants such as medications to prevent infection, reduce pain, or the like. Obviously, the liquid is intended to be a type that does no harm to the body.
After placement of the cavity marking device into the cavity, the bioabsorbable body degrades at a predetermined rate. As the body of the cavity marking device is absorbed, tissue is substituted for the bioabsorbable material. Moreover, while the body degrades, the marker, which is usually suspended substantially in the volumetric center of the body of the device, is left in the center of the cavity. Thus, during a subsequent examination, a medical practitioner having knowledge of the dimensions of the body of the cavity marking device can determine the location as well as the periphery of the biopsy cavity. The orientation of the cavity is self-evident as the marker is left in substantially the center of the cavity. For the case where multiple markers are used, the markers are usually placed in a manner showing directionality.
Both the body and the marker can be made, via radiopaque or echogenic coatings or in situ, to degrade and absorb into the patient""s body over a predetermined period of time. It is generally preferred that if the marker""s radiopacity or echogenicity is chosen to degrade over time, such degradation does not take place within at least one year after implantation of the inventive device. In this way, if a new lump or calcification (in the case of a breast biopsy) is discovered after the biopsy, such a marker will allow the physician to know the relation of such new growth in relation to the region of excised tissue. On the other hand, and as discussed below, a bioabsorption period of three months is preferred for any such coatings on the perimeter of the body itself.
This invention further includes the act of filling the biopsy cavity with a bioabsorbable liquid, aerosol or gelatinous material, preferably gelatinous collagen, allowing the material to partially solidify or gel and then placing a marker, which may have a configuration as described above, into the center of the bioabsorbable material. The gel may also be made radiopaque or echogenic by the addition of radiopaque materials, such as barium- or bismuth-containing compounds and the like, as well as particulate radio-opaque fillers, e.g., powdered tantalum or tungsten, barium carbonate, bismuth oxide, barium sulfate, to the gel.
This method may be combined with any aspect of the previously described devices as needed. For instance, one could insert a hemostatic or pain-killing substance as described above into the biopsy cavity along with the bioabsorbable material. Alternatively, a bioabsorbable marker could be inserted into a predetermined location, such as the center, of the body of bioabsorbable material.
It is within the scope of this invention that either or both of the marker or markers and the bioabsorbable body may be radioactive, if a regimen of treatment using radioactivity is contemplated.
This procedure may be used in any internal, preferably soft, tissue, but is most useful in breast tissue, lung tissue, prostate tissue, lymph gland tissue, etc. Obviously, though, treatment and diagnosis of breast tissue problems forms the central theme of the invention.
In contrast to the marker clips as described above, the cavity marking device has the obvious advantage of marking the geometric center of a biopsy cavity. Also, unlike the marking clip which has the potential of attaching to loose tissue and moving after initial placement, the marking device self-expands upon insertion into the cavity, thus providing resistance against the walls of the cavity thereby anchoring itself within the cavity. The marking device may be configured to be substantially smaller, larger, or equal to the size of the cavity, however, in some cases the device will be configured to be larger than the cavity. This aspect of the biopsy marking device provides a cosmetic benefit to the patient, especially when the biopsy is taken from the breast. For example, the resistance provided by the cavity marking device against the walls of the cavity may minimize any xe2x80x9cdimplingxe2x80x9d effect observed in the skin when large pieces of tissue are removed, as, for example, during excisional biopsies.
Although the subcutaneous cavity marking device and method described above are suited for percutaneous placement of the marker within a biopsy cavity it is not intended that the invention is limited to such placement. The device and method are also appropriate for intra-operative or surgical placement of the marker within a biopsy cavity.